The present invention relates to the display of video color measurements, and more particularly to an artistic color gamut display that combines the artistic use of color Hue, Saturation, Value and Lightness analysis with the use of a color gamut signal limit space.
With the new and different colorimetry matrix of High Definition TeleVision (HDTV) combined with the interchange of digital and analog component video via different formats, signal level measurement and monitoring related to reproducible color gamut has become more and more necessary. Various color metric displays have been created for video waveform monitors and vectorscopes. These displays, although not standardized, are useful and serve to augment traditional multi-channel waveform displays. Also since composite video, such as NTSC and PAL, is not going away as fast as some people assumed, the need for composite signal limit detection is still growing. In fact the popularity of the Vector (conventional color difference vectorscope), Diamond (U.S. Pat. No. 5,307,087) and Arrowhead (U.S. Pat. No. 5,519,440) displays is still on the rise for video production and conversion from film archives. In addition there has been an increase in sales of black-box gamut limit detectors (U.S. Pat. No. 4,707,727) and correctors or “legalizers.”
Combined with color gamut signal limit detection the Vector and Diamond displays have shown some minor utility for artistic use as well. For example, as shown in FIG. 1, the color difference Vector display is often interpreted by color correction artists as a color wheel of hues (angle) and color saturation and/or color value (radius). However the radius is not strictly color saturation or color value, and this has led to confusion. Also the mapping of color hues is not perceptually uniform, giving misleading weight when quantifying color hue errors from the Vector display. Since a valid color gamut requires that there be no negative R, G or B values and that each remain within their predetermined maximum, a valid or legal RGB cubic color space is defined where the RGB signals form the orthogonal basis. The Diamond display is useful for Red, Green, Blue (RGB) gamut or “legal color” detection since it is a projection of this RGB cubic color space, but this is not the color space preferred by artists. Artist prefer the Hue, Saturation, Value (HSV) or Hue, Lightness, Saturation (HLS) color spaces as shown in FIGS. 2 and 3.
What is desired is a new and simple display or display combination that combines the artistic use of color Hue, Saturation and Value or Lightness analysis with the use of a color gamut or “legal” signal limit space.